This invention relates to expendable immersion thermocouples and more particularly to a structure that simplifies the manufacture of the thermocouples.
Expendable immersion thermocouples were first disclosed in U.S. Pat. No. 2,999,121-Mead. Since that time, these devices have been adopted as the accepted way to take temperature measurements of molten metals. In view of the wide acceptance of such devices, millions of expendable immersion thermocouples are used annually throughout the world. In view of the wide usage of such devices, it is important that they be easy to assemble and yet rugged, durable, and accurate, so that readings made by these devices can be depended upon. Many different designs and constructions of such expendable immersion thermocouples have been proposed since the Mead invention. Typical of such improved units are those disclosed in U.S. Pat. No. 3,298,874 which discloses a one piece molded plastic part which supports the electrical conductors connected to the thermocouple and also provides mechanical support for the thermocouple until a refractory cement is poured into a cavity formed in the molded plastic part. When the refractory cement hardens a rigid unit is formed having a desirable electrical and heat insulating properties. Other expendable immersion thermocouples have taken a form such as shown in U.S. Pat. No. 3,950,992, in which a ceramic body member has cemented to one end thereof a tailpiece member formed of plastic in which the tailpiece member supports the conductors leading to the thermocouple. While such prior art devices have provided dependable expendable immersion thermocouples, the manufacture of these devices has required the time-consuming procedure of gluing the tailpiece and the body member together and permitting the glue to set before proceeding further with the final assembly of the expendable immersion thermocouple device.
It is an object of this invention to provide an improved structure that permits more rapid and easy assembly of an expendable immersion thermocouple by providing a self-latching arrangement whereby the tailpiece and the body member, when assembled mechanically, latch themselves together. Applicants' invention may best be understood from the following written description taken together with reference to the various figures of drawings.